This invention relates to surgical instruments. More particularly, this invention relates to endoscopic surgical instruments having detachable proximal and distal portions.
Endoscopic surgery is widely practiced throughout the world today and its acceptance is growing rapidly. In general, endoscopic surgery involves one or more incisions made by trocars where trocar tubes are left in place so that endoscopic surgical instruments may be inserted through the tubes. A camera or magnifying lens is often inserted through the largest diameter trocar tube (e.g. 10 mm diameter), while a cutter, dissector, or other surgical instrument is inserted through a smaller diameter trocar tube (e.g. 5 mm diameter) for purposes of manipulating and/or cutting the internal organ. Sometimes it is desirable to have several trocar tubes in place at once in order to receive several surgical instruments. In this manner, organ or tissue may be grasped with one surgical instrument, and simultaneously may be cut with another surgical instrument; all under view of the surgeon via the camera in place in the larger trocar tube.
By 1996, it is expected that more than two million additional endosurgeries will be performed per year that, in 1990, were done via open surgery (MedPRO Month, I:12, p.178). The advantages of endoscopic surgery are clear in that it is less invasive, less traumatic and recovery is typically quicker. As a result, many new instruments and devices for use in endosurgery are introduced every year. Most endoscopic instruments have similar configurations with a proximal handle, an actuation mechanism, and distal end effectors coupled by a tube through which the actuation mechanism extends. (As used herein, "proximal" means closest to the surgeon and farthest from the surgical site, while "distal" means farthest from the surgeon and closest to the surgical site.) The end effectors take many forms such as grippers, cutters, forceps, dissectors and the like. Some endoscopic instruments are provided with a ferrule on the tube so that the tube which carries the end effectors can be rotated relative to the handle. Initially, endoscopic surgical instruments were very expensive, at least partly because they had to be made very small but still be durable and reliable.
Recently, a number of "disposable" endoscopic instruments have been introduced and their use is now widely accepted. One of the advantages of disposable endoscopic instruments over reusable instruments is that because they are used only a single time, there are no sterilization problems, and no concerns about the dulling or nicking of blades or wearing of parts. However, in order to justify disposing of instruments after a single use, the instruments have to be much less expensive than the reusable tools. In order to manufacture the instruments less expensively, the disposable instruments typically use less expensive materials. As a result, the disposable instruments are less durable than the reusable instruments. Typically, the less durable components of the disposable instruments are most often the distal end effectors. However, the distal end effectors are not so fragile that they can only withstand a single use. Some surgeons therefore sterilize disposable instruments and reuse them a few times in order to reduce "per procedure costs". In addition, it will be appreciated by those skilled in the art that the proximal handle portion of the disposable instrument, is often nearly as durable as the proximal handle portion of a reusable instrument. Ultimately, therefore, it is the distal portion of the instrument which wears or breaks and mandates disposal of the entire instrument.